A comparison between illumination and position pictorial depth cues.

It has long been established that pictorial depth is created by position and illumination cues, but the relative effectiveness of these cues is unknown. This study compared position cues in line illustrations to combined position and illumination cues in color illustrations for the amount and quality of depth depiction. Results show that including illumination cues in illustrations enhances the impression of space and that illustrations of shallow space are more affected than illustrations of deep space when illumination cues are deleted.